Easy to use, basic camera with a viewfinder. Panasonic LF1 seems to fit, at the lower end of the prices. Of course, if money is not object, the Fuji X100S would be a nice choice. The Canon G15/G16 models fit your criteria as well.
I'm guessing that a superzoom type would be a bit much for their purposes.

i do not recommend the LF1 for people who don't have wonderful eye sight. i have one, and the EVF is tiny. i tried to make excuses for it, but the bottom line is it's just very small, so hard to see and shoot with.

i'm thinking maybe the panasonic FZ70. EVF isn't huge but it's definitely bigger, and maybe the slightly larger body with grip would be easier. like most cameras today, auto is pretty good. the canon SX50 or SX40 are similar but maybe the SX40 is lighter, a plus.

I'm a senior and just bought a Panasonic Lumix DMC-FZ200, which has an equivalent 600 zoom. I brought it on an African safari and got amazing photos of animals and birds. I had it set on automatic a lot, and let the camera focus. The photos turned out crystal clear. If your parents are shooting birds, this would be wonderful for them. It has both a viewfinder and screen, and it's easy to switch between them. It does take a little learning. I don't know of any digital camera that doesn't. But if you put it on automatic and let it do its job, the photos come out great. You might have to help with the set up and give them a little instruction. I used to have a Nikon point-and-shoot and I never did learn all the settings. You had to go deep within some of the settings to find what you were looking for. I never liked that camera. Am much happier with the Panasonic. And its lens is made by Leica. Don't think you can get any better than that. Hope this is helpful.